Prime and Composite Numbers

Prime Numbers

A prime number is a whole number greater than 1, that only has two factors which are itself and one. (It can be divided without a remainder only by 1 or itself.)
For example, 17 can be divided only by 17 and by 1.

Composite Numbers

A composite number is a positive integer that can be formed by multiplying together two smaller positive integers. A composite number has factors in addition to one and itself. Composite numbers are exactly the numbers that are not prime. The smallest composite number is 4, because 2 x 2 = 4.
All even numbers are divisible by two and so all even numbers greater than two are composite numbers.
All numbers that end in five are divisible by five. Therefore all numbers that end with five and are greater than five are composite numbers.